1. Field of the Invention
The present invention relates generally to electromagnetic actuators and more specifically to actuators such as trip mechanisms found in circuit breakers, accessories of circuit breakers, relays, or actuators.
2. Discussion of the Related Art
Referring to FIG. 1, in a known armature-yoke system 11, the input current in a conductor (not shown) within the yoke 13 creates a magnetic field in the yoke 13, the armature 14 and the magnetic air gap (g) between them. This results in a magnetic torque that rotates the armature 14 towards the stationary yoke 13 and moves the trip bar 16. The hammer 18 is then released and strikes a target device, e.g. a breaker latch release (not shown), as is understood by those in the art.
The magnetic torque on the armature 14 is adjusted by turning a screw 20 to set the magnetic air gap (g). The smaller the magnetic air gap (g) the higher the magnetic torque. However, as the armature 14 moves closer to the yoke 13, the force of the return spring 22, attached to the bell crank 24 for resetting the armature 14, also increases, thus counteracting the effect of the magnetic torque. The net result is a reduced sensitivity of the system to gap adjustment and a lower net torque on the armature 14. This may not be desirable in applications where the input current is low.